Wheel fairing deflecting wind onto lower wheel

ABSTRACT

An upper wheel fairing for increasing the propulsive efficiency of a wheeled vehicle having wheels otherwise exposed to headwinds, comprising a deflector panel or skirt assembly mounted upstream in front of a rearward wheel set, extending downward not lower than the axle, and arranged to deflect headwinds from impinging upon the high drag-inducing upper wheel surfaces downward onto the low-drag lower wheel surfaces.

BACKGROUND

1. Field

The present embodiment relates to an appartus for the reduction ofaerodynamic drag on vehicles having wind-exposed wheels of a wheelassembly mounted underneath the vehicle body, such as on largecommercial trucks.

2. Description of Prior Art

Vehicles having wind-exposed wheels are particularly sensitive toexternal headwinds reducing propulsive efficiency. Drag force on exposedwheels increases more rapidly on upper wheel surfaces than on vehicleframe surfaces, causing a non-linear relation from rising wind speedsbetween net drag forces on vehicle frame surfaces versus net drag forceson vehicle wheel surfaces.

Since upper wheel surfaces are moving against the wind at more than thevehicle speed, the upper wheel drag forces contribute more and more ofthe total vehicle drag as external headwinds rise. Thus, as externalheadwinds rise, a greater fraction of the net vehicle drag is shiftedfrom vehicle frame surfaces to upper wheel surfaces.

Moreover, upper wheel drag forces must be overcome by a propulsivecounterforce applied at the axle. Such propulsive counterforces suffer amechanical disadvantage against the upper wheel drag forces, since eachnet force is applied about the same pivot point located at the bottomwhere the wheel is in stationary contact with the ground. Thismechanical advantage that upper wheel drag forces have over propulsivecounterforces further augments the effective vehicle drag that exposedupper wheels contribute under rising headwinds. As a result of thesemagnified effects of upper wheel drag on resisting vehicle propulsion,vehicle drag is more effectively reduced by reducing the aerodynamicpressure on the upper wheel surfaces while leaving the lower wheelsurfaces exposed to impinging headwinds.

Furthermore, shielding the lower wheel surfaces can cause a net increasein vehicle drag, and a loss in propulsive efficiency. Not only does thepropulsive counterforce applied at the axle have a mechanical advantageover the lower wheel drag forces, but shielding the lower wheel surfacesusing a deflector attached to the vehicle body shifts the drag forcefrom being applied at the lower wheel to an effective higher elevationat the axle, thereby negating any mechanical advantage of a propulsivecounteforce applied at the axle has over the lower wheel drag force. Asa result, aerodynamic trailer skirts in widespread use today areunnecessarily inefficient, since they generally extend below the levelof the axle.

Nevertheless, extended height trailer skirts have been shown to improvepropulsive efficiency, since they reduce the aerodynamic pressure on theupper wheel surfaces, which cause the vast majority of wheel drag andvirtually all of the loss in vehicle propulsive efficiency due to wheeldrag. However, the extended skirts shown in the art also impact theaerodynamic pressure on the lower wheel surfaces, where propulsivecounterforces delivered at the axle have a mechanical advantage overlower wheel drag forces.

As mentioned, diverting wind from impinging the lower wheel surfacesactually increases overall vehicle drag, reducing propulsive efficiency.Deflecting wind from impinging these lower wheel surfaces transfers theaerodynamic pressure from these slower moving surfaces also suffering amechanical disadvantage, to faster moving vehicle body surfaces havingno mechanical advantage over propulsive counterforces, therebyincreasing vehicle drag.

Nevertheless, numerous examples in the art demonstrate the currentpreference for aerodynamic skirts extending to below the level of theaxle. For example, in patents U.S. Pat. No. 7,942,471 B2, US2006/0152038 A1, U.S. Pat. No. 6,974,178 B2, U.S. Pat. No. 8,303,025 B2,U.S. Pat. No. 7,497,502 B2, U.S. Pat. No. 8,322,778 B1, U.S. Pat. No.7,806,464 B2, US 2010/0066123 A1, U.S. Pat. No. 8,342,595 B2, U.S. Pat.No. 8,251,436 B2, U.S. Pat. No. 6,644,720 B2, U.S. Pat. No. 5,280,990,U.S. Pat. No. 5,921,617, U.S. Pat. No. 4,262,953, U.S. Pat. No.7,806,464 B2, US 2006/0252361 A1, U.S. Pat. No. 4,640,541 all make nomention of the differing relationships between upper wheel drag forcesand lower wheel drag forces affecting vehicle propulsive efficiency.Most of these patents depict figures showing skirts extending well belowthe level of the axle. And an examination of leading trailer skirtmanufacturers shows the prevalence for extended height skirts currentlyfor sale and needed to meet California carbon emission requirements.

Furthermore, a recent in-depth wind tunnel study sponsored the the USDepartment of Energy and conducted at a pre-eminent research institutionof the United States government, Lawerence Livermore Laboratory waspublished Mar. 19, 2013, “Aerodynamic drag reduction of class 8 heavyvehicles: a full-scale wind tunnel study”, Ortega, et. al, and concludedthat trailer skirts are one of the most effective means to reduce dragon large tractor-trailer trucks. A large number of trailer skirtconfigurations were tested in this study, which employed traditionaltechniques for measuring total drag on the vehicle. Due to the nonlineareffects of upper wheel drag in rising headwinds, such techniques canproduce inaccurate measurements of gains in propulsive efficiency forvehicles having wheels exposed to headwinds. Thus, as yet this importantrelationship of upper wheel drag more predominately affecting overallvehicle drag—and especially over lower wheel drag which is oftencomparitively negligible and suffers a mechanical disadvantage againstpropulsive counterforces applied at the axle—has gone unrecognized.

And in the patent art cited above, several patents such as U.S. Pat. No.4,262,953, U.S. Pat. No. 4,640,541, US 2006/0252361 A1, U.S. Pat. No.7,806,464 B2, U.S. Pat. No. 8,322,778 and others depict wind deflectingpanels generally spanning the lateral width of the trailer, therebyinducing unnecessary drag by blocking air otherwise funneled between thewheels. Funneled air into the rear of the vehicle can reduce pressuredrag on the vehicle. In the art, there are numerous other examples ofdevices attempting to enhance this vehicle drag reducing effect.

Finally, also in the cited art above, several patents such as US2010/0066123 A1, U.S. Pat. No. 8,342,595 B2 and U.S. Pat. No. 8,251,436B2 depict wind deflecting panels in front of the wheels of the trailerextending to well below the level of the axle, thereby inducingunnecessary vehicle drag by transferring drag from the slower movinglower wheel surfaces having a mechanical disadvantage, to the fastermoving vehicle body and frame. In the art, there are numerous otherexamples of devices attempting to enhance this wheel drag reducingeffect.

SUMMARY

All embodiments comprise either wind-deflecting skirts or panels for useon vehicles having wind-exposed wheels on a wheel assembly mountedunderneath the vehicle body, such as on the trailers of large commercialtrucks. Each embodiment is designed to deflect vehicle headwinds fromdirectly impinging the upper wheel surfaces—the predominate draginducing surfaces on a wheel—and onto the lower wheel surfaces—the leasteffective drag inducing surfaces on a wheel—thereby reducing vehicledrag and increasing vehicle propulsive efficiency. Each embodiment isalso designed to keep the lower wheel surfaces exposed to headwinds.Since propulsive counterforces applied at the axle have a naturalmechanical advantage over lower wheel drag forces, deflecting headwindsonto fully-exposed lower wheels surfaces also increases vehiclepropulsive efficiency.

An embodiment comprises an inclined aerodynamic deflector panel assemblydesigned to deflect headwinds otherwise impinging upper wheel surfacesdownward onto lower wheel surfaces of a trailing wheel set on eitherside of the wheel assembly. The deflector panel assembly can be agenerally flat panel tilted to deflect air downward onto the lower wheelsurfaces, or a panel with perpendicular end plates projection forwardforming a U-shaped channel arranged to funnel air downward onto thelower wheel surfaces. The deflector panel assembly extends down from thevehicle body to no lower than the level of the axle of the wheelassembly, and may included wheel skirts covering the trailing wheelsets. The panel may also be extended across the lateral width of thetrailer to deflect headwinds below the trailing cental axle assembly.

An embodiment comprises an aerodynamic skirt panel assembly designed todeflect headwinds otherwise impinging upper wheel surfaces downward ontolower wheel surfaces of a trailing wheel set on either side of the wheelassembly. Toward the front end, the skirt panel assembly is locatedsubstantially inboard toward the centerline of the vehicle. Toward therear end, the skirt panel assembly diverges rapidly to the outside ofthe trailing wheel set in order to divert headwinds in part onto thelower wheel surfaces. The skirt assembly extends down from the vehiclebody no lower than the level of the axle of the wheel assembly, and mayincluded wheel skirts covering the trailing wheel sets.

DESCRIPTION OF THE DRAWINGS

While one or more aspects pertain to most wheeled vehicles not otherwisehaving fully shielded wheels that are completely protected from oncomingheadwinds, the embodiments can be best understood by referring to thefollowing figures.

In FIG. 1, an inclined aerodynamic deflector panel assembly is mountedunderneath the trailer of an industrial truck in front of a wheel set ofthe rear wheel assembly.

In FIG. 2, the inclined aerodynamic wheel deflector panel assembly ofFIG. 1 is shown mounted on the trailer as viewed in cross-section fromthe front of the vehicle. Two deflector panel assemblies are shown, eachas mounted in front of one of the wheel sets of the rear wheel assembly.

In FIG. 3, an inclined aerodynamic deflector panel assembly whichappears in side view similar to as shown in FIG. 1, is shown mounted onthe trailer as viewed in cross-section from the front of the vehicle.

In FIG. 4, a channeled aerodynamic deflector panel assembly is mountedunderneath the trailer of an industrial truck in front of the rear wheelassembly.

In FIG. 5, the channeled aerodynamic wheel deflector panel assembly ofFIG. 4 is shown mounted on the trailer as viewed in cross-section fromthe front of the vehicle. Two deflector panel assemblies are shown, eachas mounted in front of one of the wheel sets of the rear wheel assembly.

In FIG. 6, the channeled aerodynamic deflector panel assembly whichappears in side view similar to as shown in FIG. 4, is shown mounted onthe trailer as viewed in cross-section from the front of the vehicle.

In FIG. 7, a channeled aerodynamic deflector panel and wheel skirtassembly is mounted underneath the trailer of an industrial truck infront of a wheel set of the rear wheel assembly.

In FIG. 8, an aerodynamic wheel deflector panel is mounted underneaththe trailer of an industrial truck in front of a wheel set of the rearwheel assembly.

In FIG. 9, a aerodynamic deflector panel and wheel skirt assembly ismounted underneath the trailer of an industrial truck in front of therear wheel assembly.

In FIG. 10, an aerodynamic deflector skirt assembly is mountedunderneath the trailer of an industrial truck in front of the rear wheelassembly.

In FIG. 13, the aerodynamic deflector skirt assembly of FIG. 10 is shownfrom below the vehicle.

In FIG. 14, the aerodynamic deflector skirt assembly together with awheel skirt panel assembly is mounted to the trailer of an industrialtruck.

FIG. 11 is a front cycle wheel assembly, as typically found on a bicycleor motorcycle, where a fairing is attached and positioned as shown toeach interior side of the fork assembly, thereby shielding the upper-and front-most surfaces of the spoked wheel from oncoming headwinds.

FIG. 12 is a series of curves showing the results of an analysis of thedrag mechanics on a bicycle with shielded upper wheels, indicating thata bicycle with shielded upper wheels is faster when facing headwinds.Several curves are displayed, as examples of different bicycles eachhaving a different proportion of wheel-drag to total-vehicle-drag.

FIG. 17 shows a plot of calculated average moments—about the groundcontact point—of drag force, that are exerted upon rotating wheelsurfaces as a function of the elevation above the ground. The relativedrag forces are determined from calculated wind vectors for the rotatingsurfaces on a wheel moving at a constant speed of V, and plotted forseveral different wind and wheel-surface shielding conditions.Specifically, relative magnitudes in average drag moments about theground contact point as a function of elevation are plotted, for eightconditions: comparing with (dashed lines) and without (solid lines)shielding covering the upper third of wheel surfaces, for tailwindsequal to half the vehicle speed; for null headwinds; for headwinds equalto half the vehicle speed; and for headwinds equal to the vehicle speed.The rising solid curves plotted show the highest moments to be near thetop of the wheel, while the dashed curves show the effect of the uppershield in substantially reducing the average drag moments on therotating wheel.

FIG. 18 shows a plot of calculated relative drag torque exerted uponrotating wheel surfaces as a function of elevation above the ground. Therelative total drag torques are determined from the calculated averagemoments in combination with the chord length at various elevations on awheel moving at a constant speed of V, for several different wind andwheel-surface shielding conditions. Relative magnitudes in total dragtorque about the ground contact point as a function of elevation areplotted for eight conditions: comparing with (dashed lines) and without(solid lines) shielding covering the upper third of wheel surfaces, fortailwinds equal to half the vehicle speed; for null headwinds; forheadwinds equal to half the vehicle speed; and for headwinds equal tothe vehicle speed. The areas under the plotted curves represent thetotal torque from frictional drag on wheel surfaces. Comparing thedifferences in area under the plotted curves reveals the general trendof the upper shield to substantially reduce the total drag torque on therotating wheel.

FIG. 24 (Prior Art) is a diagram of a wheel rolling on the groundrepresenting typical prior art models, showing the net pressure dragforce (P) exerted upon the forward wheel vertical profile—which moves atthe speed of the vehicle—being generally centered near the axle of thewheel and balanced against the propulsive force (A) applied at the axle.

FIG. 25 is a diagram of a wheel rolling on the ground, showing the netfriction drag force (F) upon the wheel surfaces—which move at differentspeeds depending on the elevation from the ground—being offset from theaxle and generally centered near the top of the wheel. A ground reactionforce (R)—arising due to the drag force being offset near the top of thewheel—is also shown. The force (A) applied at the axle needed toovercome the combination of drag forces (F+P) and reaction force (R) isalso shown.

DESCRIPTION OF WHEEL DRAG MECHANICS

As mentioned, drag force on exposed wheels increases more rapidly onupper wheel surfaces than on vehicle frame surfaces, causing anon-linear relation from rising wind speeds between net drag forces onvehicle frame surfaces versus net drag forces on vehicle wheel surfaces.Thus, vehicles having wind-exposed wheels are particularly sensitive toexternal headwinds reducing propulsive efficiency. As a result, thereexists a need for an improved aerodynamic deflector and skirt for use onindustrial trucks and trailers.

Because of this rising dominance of wheel drag in rising headwinds—dueto the non-linear relation from rising wind speeds between net dragforces on vehicle frame surfaces versus net drag forces on vehicle wheelsurfaces—a discussion of the wheel drag mechanics central to thisnon-linear relationship is presented herein. The upper wheel fairing isdescribed below as a simple solution for reducing vehicle drag in risingheadwinds on a cycle, and is presented herein as background for thepresent embodiment.

The shielding provided by fairing 1 in FIG. 11 is particularly effectivesince aerodynamic forces exerted upon exposed vehicle surfaces aregenerally proportional to the square of the effective wind speedimpinging thereon. Moreover, the power required to overcome these dragforces is generally proportional to the cube of the effective windspeed. Thus, it can be shown that the additional power required toovercome these drag forces in propelling a vehicle twice as fast over afixed distance, in half the time, increases by a factor of eight. Andsince this power requirement is analogous to rider effort—in the case ofa bicycle rider—it becomes critical to shield the most criticaldrag-inducing surfaces on a vehicle from oncoming headwinds.

FIG. 12 shows the results of an analysis of the drag mechanics on abicycle with shielded upper wheels. The curves indicate that a bicyclewith shielded upper wheels is faster when facing headwinds. Moreover,the gains in propulsive efficiency are shown to quickly increase in onlya modest headwind, but continue to rise as headwinds increase further.

In any wheel used on a vehicle, and in the absence of any externalheadwinds, the effective horizontal wind speed at a point on the wheelat the height of the axle is equal to the ground speed of the vehicle.Indeed, the effective headwind speed upon any point of the rotatingwheel depends on that point's current position with respect to thedirection of motion of the vehicle.

Notably, a point on the moving wheel coming into direct contact with theground is necessarily momentarily stationary, and therefore is notexposed to any relative wind speed, regardless of the speed of thevehicle. While the ground contact point can be rotating, it is nottranslating; the contact point is effectively stationary. And points onthe wheel nearest the ground contact point are translating with onlyminimal forward speed. Hence, drag upon the surfaces of the wheelnearest the ground is generally negligible.

Contrarily, the topmost point of the wheel assembly (opposite theground) is exposed to the highest relative wind speeds: generally atleast twice that of the vehicle speed. And points nearest the top of thewheel are translating with forward speeds substantially exceeding thevehicle speed. Thus, drag upon the surfaces of the upper wheel can bequite substantial. Lower points on the wheel are exposed to lessereffective wind speeds, approaching a null effective wind speed—and thusnegligible drag—for points nearest the ground.

Importantly, due to the rotating geometry of the wheel, it can be shownthat the effective combined frictional drag force exerted upon the wheelis typically centered in closer proximity to the top of the wheel,rather than centered closer to the axle as has been commonly assumed inmany past analyses of total wheel drag forces. While the net pressure(or form) drag (P) force on the forwardly facing profile of the wheel isgenerally centered with elevation and directed near the axle on thewheel (as shown in FIG. 24), the net frictional drag force (F) upon themoving surfaces is generally offset to near the top of the wheel (asshown in FIG. 25).

Indeed, it is near the top of the wheel where the relative winds areboth greatest in magnitude, and are generally oriented most directlyopposed to the forward motion of rotating wheel surfaces. Moreover, inthe absence of substantial external headwinds, the frictional dragexerted upon the lower wheel surfaces contributes relatively little tothe net drag upon the wheel, especially when compared to the drag uponthe upper surfaces. The combined horizontal drag forces (from pressuredrag from headwinds deflected by both the leading and trailing wheelforwardly facing profiles, and from frictional drag from headwindsimpinging upon the forwardly moving surfaces) are thus generallyconcentrated near the top of the wheel under typical operatingconditions. Moreover, with the faster relative winds being directedagainst the uppermost wheel surfaces, total drag forces combine near thetop to exert considerable retarding torque upon the wheel.

As mentioned, the horizontal drag forces are primarily due to bothpressure drag forces generally distributed symmetrically across theforwardly facing vertical profiles of the wheel, and to winds infrictional contact with moving surfaces of the wheel. Pressure dragforces arise primarily from the displacement of air from around theadvancing vertical profile of the wheel, whose circular outline moves atthe speed at the vehicle. As discussed above, since the entire circularprofile moves uniformly at the vehicle speed, the displacement of airfrom around the moving circular profile is generally uniformlydistributed with elevation across the forwardly facing vertical profileof the wheel. Thus, these pressure drag forces (P, as shown in FIG. 24and FIG. 25) are also generally evenly distributed with elevation acrossthe entire forwardly facing vertical profile of the wheel, and centerednear the axle. And these evenly distributed pressure drag forces arisegenerally in proportion only to the effective headwind speed of thevehicle.

Frictional drag forces (F, as shown FIG. 25), however, are concentratednear the top of the wheel where moving surfaces generally exceed vehiclespeed—while the lower wheel surfaces move at less than the vehiclespeed. Since drag forces are generally proportional to the square of theeffective wind speed, it becomes apparent that with increasing windspeed, that these upper wheel frictional drag forces directed upon themoving surfaces increase much more rapidly than do pressure drag forcesdirected upon the forward profile of the wheel. Indeed, these frictiondrag forces generally arise in much greater proportion to an increasingeffective headwind speed of the vehicle. Nevertheless, these increasedfrictional drag forces being directed on the upper wheel is only apartial factor contributing to augmented wheel drag forces beingresponsible for significantly retarded vehicle motion.

Significantly, both types of drag forces can be shown to exert momentsof force pivoting about the point of ground contact. And as such, eithertype of drag force exerted upon the upper wheel retards vehicle motionconsiderably more than a similar force exerted upon a substantiallylower surface of the wheel. Minimizing these upper wheel drag forces istherefore critical to improving propulsive efficiency of the vehicle.

Also important—and due to the rotating geometry of the wheel—it can beshown that the vehicle propulsive force on the wheel appliedhorizontally at the axle must substantially exceed the net opposing dragforce exerted near the top of the wheel. These forces on a wheel areactually leveraged against each other, both pivoting about the samepoint—the point on the wheel which is in stationary contact with theground—and which is constantly changing lateral position with wheelrotation. Indeed, with the geometry of a rolling wheel momentarilypivoting about the stationary point of ground contact, the lateral dragand propulsive forces each exert opposing moments of force on the wheelcentered about this same point in contact with the ground.

Furthermore, unless the wheel is accelerating, the net torque from thesecombined moments on the wheel must be null: The propulsive momentgenerated on the wheel from the applied force at the axle mustsubstantially equal the opposing moment from drag forces centered nearthe top of the wheel (absent other resistive forces, such as bearingfriction, etc.). And the propulsive moment generated from the appliedforce at the axle has a much shorter moment arm (equal to the wheelradius) than the opposing moment from the net drag force centered nearthe top of the wheel (with a moment arm substantially exceeding thewheel radius)—since both moment arms are pivoting about the samestationary ground contact point. Thus, for these opposing moments toprecisely counterbalance each other, the propulsive force applied at theaxle—with the shorter moment arm—must substantially exceed the net dragforce near the top of the wheel.

In this way, the horizontal drag forces exerted upon the upper surfacesof the wheel are leveraged against opposing and substantially magnifiedforces at the axle. Hence, a relatively small frictional drag forcecentered near the top of the wheel can have a relatively high impact onthe propulsive counterforce required at the axle. Shielding these upperwheel surfaces can divert much of these headwind-induced drag forcesdirectly onto the vehicle body, thereby negating much of the retardingforce amplification effects due to the pivoting wheel geometry.

Moreover, since the propulsive force applied at the axle exceeds thecombined upper wheel drag forces, a lateral reaction force (R, as shownin FIG. 25) upon the wheel is necessarily developed at the groundcontact point, countering the combined unbalanced propulsive and dragforces on the wheel: Unless the wheel is accelerating, the reactionforce at the ground, together with the upper wheel net drag forces(F+P), combine (A=F+R+P, as shown in FIG. 25) to countervail the lateralpropulsive force (A) applied at the axle. This reaction force istransmitted to the wheel through frictional contact with the ground. Inthis way, an upper wheel drag force is further magnified against theaxle. For these multiple reasons, it becomes crucial to shield the upperwheel surfaces from exposure to headwinds.

Given that the propulsive force (A) applied at the axle must overcomeboth the net wheel drag forces (F+P) and the countervailing lowerreaction force (R) transmitted through the ground contact point, it canbe shown that the net drag force upon the upper wheel can oppose vehiclemotion with nearly twice the sensitivity as an equivalent drag forceupon the static frame of the vehicle. Hence, shifting the impact ofupper wheel drag forces to the static frame can significantly improvethe propulsive efficiency of the vehicle.

Furthermore, as drag forces generally increase in proportion to thesquare of the effective wind speed, the more highly sensitive upperwheel drag forces increase far more rapidly with increasing headwindspeeds than do vehicle frame drag forces. Thus, as the vehicle speedincreases, upper wheel drag forces rapidly become an increasingcomponent of the total drag forces retarding vehicle motion.

And given the greater sensitivity of speed-dependent upper wheel dragforces—as compared against vehicle frame drag forces—to the retarding ofvehicle motion, considerable effort should first be given to minimizingupper wheel drag forces. And shielding the faster-moving uppermostsurfaces of the wheel assembly from oncoming headwinds, by using thesmallest effective fairing assembly, is an effective means to minimizeupper wheel drag forces.

Contrarily, drag forces on the lower wheel generally oppose vehiclemotion with reduced sensitivity compared to equivalent drag forces onthe static frame of the vehicle. Propulsive forces applied at the axleare levered against lower wheel drag forces, magnifying their impactagainst these lower wheel forces. Shielding lower wheel surfaces cangenerally negate this mechanical advantage, and can actually increaseoverall drag on the vehicle.

Moreover, as discussed above, headwinds on the static frame generallyexceed the speed of winds impinging the lower surfaces of the wheel.Hence, frictional drag forces on the lower wheel surfaces are greatlyreduced. Thus, it is generally counterproductive to shield the wheelbelow the level of the axle. Drag on a vehicle is generally minimizedwith upper wheel surfaces shielded from headwinds and with lower wheelsurfaces exposed to headwinds.

Wheel drag sensitivity to retarding vehicle motion becomes even moresignificant in the presence of external headwinds. With externalheadwinds, the effective wind speed impinging the critical upper wheelsurfaces can well exceed twice the vehicle speed. Shielding protects theupper wheel surfaces both from external headwinds, and from headwindsdue solely to vehicle motion.

Indeed, wheel surfaces covered by the shield are exposed to winds duesolely to wheel rotation; headwinds are deflected. The effective dragwinds beneath the shield are generally directed tangentially to rotatingwheel surfaces, and vary in proportion to radial distance from the axle,reaching a maximum speed at the wheel rim equal to the vehicle speed,regardless of external headwinds. Since drag forces vary generally inproportion to the square of the wind speed, the frictional drag forcesare considerably reduced on shielded upper wheel surfaces. Using thesewind shields, shielded wheel surfaces are exposed to substantiallyreduced effective wind speeds—and to generally much less than half ofthe drag forces without shielding.

Diminished drag forces from external headwinds impinging the slowermoving lower surfaces of a rolling wheel generally oppose wheel motionwith much less retarding torque than drag forces from winds impingingthe faster upper surfaces. Indeed, tests demonstrate that with uppershields installed on a suspended bicycle wheel, the wheel will spinnaturally in the forward direction when exposed to headwinds. Withoutthe shields installed, the same wheel remains stationary when exposed toheadwinds, regardless of the speed of the headwind. And an unshieldedspinning wheel will tend to stop spinning when suddenly exposed to aheadwind. This simple test offers an explanation for the unexpectedresult and demonstrates that by minimally shielding only the upper wheelsurfaces from external headwinds, the overall drag upon the rotatingwheel can be substantially reduced.

Furthermore, as external headwinds upon a forwardly rotating vehiclewheel add relatively little frictional drag to the lower wheelsurfaces—which move forward at less than the vehicle speed—but add farmore significant drag to the upper wheel surfaces, which move forwardfaster than the vehicle speed and which can more significantly retardvehicle motion, shielding the upper wheel surfaces against headwinds isparticularly beneficial. Since drag forces upon the wheel are generallyproportional to the square of the effective wind speed thereon, and theadditional drag on the wheel—and thereby on the vehicle—increasesrapidly with headwinds, shielding these upper surfaces greatly reducesthe power required to propel the vehicle. Moreover, the relativeeffectiveness of shielding upper wheel surfaces generally increases withincreasing headwinds.

An examination of the retarding wind vectors on a rotating wheel canreveal the large magnitude of drag retarding moments upon the uppermostwheel surfaces, relative to the lower wheel surfaces. And an estimate ofthe frictional drag torque on the wheel can be determined by firstcalculating the average moments due to drag force vectors at variouspoints—all pivoting about the ground contact point—on the wheel (resultsshown plotted in FIG. 17), and then summing these moments at variouswheel elevations above the ground and plotting the results (FIG. 18).The area under the resulting curve (shown in FIG. 18 as a series ofcurves representing various headwind conditions) then represents thetotal frictional drag (absent profile drag) torque upon the wheel.

In order to determine the relationship between this torque and elevationon the wheel, the magnitudes of the drag wind vectors that areorthogonal to their corresponding moment arms pivoting about the pointof ground contact must first be determined. These orthogonal vectorcomponents can be squared and then multiplied by the length of theircorresponding moment arms, in order to determine the relative momentsdue to drag at various points along the wheel rim.

The orthogonal components of these wind vectors tend to increaselinearly with elevation for points on the rim of the wheel, and also forpoints along the vertical mid-line of the wheel. Calculating the momentsalong the vertical mid-line of the wheel can yield the minimum relativedrag moments at each elevation. Calculating an average of the maximumdrag moment at the rim combined with the minimum drag moment along themid-line can then yield the approximate average drag moment exerted ateach elevation upon the wheel. Multiplying this average drag moment bythe horizontal rim-to-rim chord length can yield an estimate of the dragtorque exerted upon the wheel at each elevation level (FIG. 18). Thesecalculations are simply determined from the geometry of the rotatingwheel; the object of this analysis is to determine the likely relativemagnitudes of drag torques upon the wheel at various elevations.

From the resulting plots (FIG. 18), it can be estimated that theuppermost approximate one-third section of the wheel likely contributesmost of the overall drag torque upon the wheel. Thus, by shielding thisupper section from headwinds, drag torque can be considerably reduced.With upper-wheel shielding, as noted above, the relative winds beneaththe shield are due mostly to wheel rotation, and are generally directedtangentially to the wheel. The resulting drag torque under the shieldedsections can then be determined as above, and compared with theunshielded drag torque for similar headwind conditions.

These calculations—generally confirmed by tests—indicate a substantialreduction in retarding drag torque upon the shielded upper wheelsurfaces. In the absence of external headwinds, the plots of FIG. 18indicate that shielding the uppermost approximate one-third section ofthe wheel can reduce the drag torque of this section considerably, by asmuch as 75 percent. Moreover, repeating calculations and testing with anexternal headwind equal to the vehicle speed indicates that upper wheelshielding can reduce the comparative upper wheel drag torque of thissection by still more, perhaps by as much as 90 percent. Hence, thepotential effectiveness of shielding upper wheel surfaces can besignificant, especially with surfaces having higher drag sensitivities,such as wheel spoke surfaces.

As discussed above, since upper wheel drag forces are leveraged againstthe axle—thereby magnifying the propulsive counterforce required at theaxle—an increase in drag force on the wheels generally retards vehiclemotion much more rapidly than does an increase in other vehicle dragforces. And while under external headwind conditions, the total drag ona vehicle with wheels exposed directly to headwinds increases still morerapidly with increasing vehicle speed.

Shielding upper wheel surfaces effectively lowers the elevation of thepoint on the wheel where the effective net drag force is exerted,thereby diminishing the magnifying effect of the propulsive counterforcerequired at the axle, as discussed above. As a result, the reduction indrag force upon the vehicle achieved by shielding the upper wheelsurfaces is comparatively even more significant with increasing externalheadwinds. Shielding these upper wheel surfaces can thereby improverelative vehicle propulsion efficiency under headwinds by an evengreater margin than under null wind conditions.

Moreover, shielding these upper wheel surfaces can be particularlybeneficial to spoked wheels, as round spokes can have drag sensitivitiesmany times greater than that of more streamlined surfaces. As roundspokes—in some configurations—can have drag coefficients ranging fromone to two orders of magnitude greater than corresponding smooth,streamlined surfaces, shielding the spokes of the upper wheel fromexternal wind becomes particularly crucial in reducing overall drag uponthe wheel.

Accordingly—given these multiple factors—a relatively small streamlinedfairing attached to the vehicle structure and oriented to shield theupper surfaces of the wheel assembly from oncoming headwindssubstantially reduces drag upon the wheel, while minimizing total dragupon the vehicle.

DETAILED DESCRIPTION

Various embodiments are described below in detail, each providing meansto deflect headwinds from directly impinging the upper wheel surfacesand onto the lower wheel surfaces of a trailing wheel assembly, therebyreducing vehicle drag and increasing propulsive efficiency.

First Embodiment FIGS. 1 and 2

As shown in FIGS. 1 and 2, an embodiment comprises an inclinedaerodynamic wheel deflector panel assembly 20 attached to and mountedunderneath the body of a trailer 16 for a commercial vehicle. Theinclined wheel deflector panel assembly 20 is located forward of therear wheel assembly 17 and located directly in front of a trailing wheelset 18 which would otherwise be exposed to headwinds when the vehicle isin forward motion. The inclined wheel deflector panel assembly 20 isplanar in shape, mounted inclined in a forwardly-angled orientation withthe upper edge more forwardly located and the lower surface morerearwardly located on the vehicle. The inclined wheel deflector panelassembly 20 spans the lateral width of the trailing wheel set 18 of thetrailing rear wheel assembly 17 located on either side of the vehicle.The inclined wheel deflector panel assembly 20 extends no lower than thelevel of the axle 19 and is located proximal to the trailing wheel set18 in order to deflect upper wheel headwinds onto the exposed lowerwheel surfaces.

It can be concluded from the discussion of wheel drag mechanics above,that since propulsive counterforces applied to the wheel at the axlehave a mechanical advantage over lower wheel drag forces—which arenecessarily applied to the wheel below the level of the axle—directingupper wheel headwinds onto the lower wheel surfaces can significantlyreduce overall vehicle drag and improve propulsive efficiency. Thereasons for these gains in vehicle efficiency become apparent by furtherconsidering how wheel drag forces compare with vehicle body drag forces.

As discussed earlier, drag forces on the wheel must be countered by apropulsive force from the vehicle body applied at the axle. And it canbe established that drag forces on the upper wheel have a mechanicaladvantage over countervailing propulsive counterforces applied at theaxle. And with the wheel deflector assembly attached to the vehiclebody, drag on the deflector must also be countervailed by a propulsivecounterforce applied to the vehicle body at a propulsively-driven axle.

Thus, in order to determine the relative difference in total vehicledrag between the traditional extended height deflector divertingheadwinds from impinging both the upper and the lower wheels, and theimproved reduced height deflector with the lower wheels fully-exposed toheadwinds, the added vehicle drag derived from the surface of thedeflector panel extending below the level of the axle must be comparedagainst the vehicle drag arising from the corresponding additionalsurfaces of the lower wheel otherwise shielded by the extendeddeflector. And as already established above, the relative effects ofthese resistive forces on vehicle propulsion are non-linearly related,and vary considerably with increasing headwinds: for vehicles facingfaster external headwinds the nonlinear effects quickly increase, asdiscussed above and as shown in FIG. 12, where the results of ananalysis of the drag mechanics of a bicycle facing increasing headwindsshows rapid increases in propulsive efficiency by shielding the upperwheels.

Moreover, since propulsive counterforces applied at the axle have amechanical advantage over drag forces on the lower wheel surfaces, asimple comparison of the net drag force on either surface alone—eitheron the lower wheel or on the extender deflector surface—is insufficientto determine the relative effect each has on vehicle propulsiveefficiency. Instead, the magnitudes of the drag force from each surfacemust be reflected to an equivalent force applied at the same axle andcompared against one another.

For the lower wheel surfaces, the net drag force as applied against theaxle is diminished by leveraging about the point of ground contact. Forthe lower deflector panel surface, the drag force is directed againstthe axle without magnification since it is transmitted directly throughthe body and frame of the vehicle. Although another axle of the vehiclemay be the used as the propulsively-driven axle, the two net drag forcesmust be compared as reflected at the same affected axle in order togauge their relative effects on overall vehicle drag.

For the lower deflector surface, the drag force on the surface is—likeother vehicle body drag forces—directly countervailed by the propulsivecounterforce applied at the driven axle. For the lower wheel surfaces,the situation is more complicated due both to the mechanical advantagethat the propulsive forces have over lower wheel drag forces, and to theeffects that the summation moments of drag force (FIG. 17) at differentpoints on the rotating wheel have on the net lower wheel drag force.

As noted earlier in the discussion of wheel drag mechanics, and as shownin the plot of FIG. 18, the average drag torque exerted against thelower wheel surfaces has far less impact on the total wheel drag thandoes the average drag torque exerted against the upper wheel surfaces.This is due largely to the pivoting geometry of the rotating wheel,where wheel forces are levered about the same stationary point of groundcontact at the bottom of the wheel. Owing in part to their longer momentarms, drag forces applied to the upper wheel produce far greaterresistive torques on the wheel than do drag forces applied to the lowerwheel.

Consequently, drag forces on the upper wheel surfaces are ideallyshifted to the lower wheel surfaces in order to benefit the propulsiveefficiency of the vehicle. As a result, deflecting headwinds from theupper wheel surfaces onto the lower wheel surfaces can substantiallyreduce overall vehicle drag and improve propulsive efficiency.

And in the case of industrial trucks having large wheels with largertires, the relative effects of resistive pressure drag forces on thewheel over frictional drag forces is excerbated over that of a spokedbicycle wheel as described above in the discussion of the wheel dragmechanics. As mentioned, the spoked wheels with thin tires and rims usedon a bicycle can produce significant frictional drag effects resistingvehicle propulsion. Trucks with smooth wheels and tires are moresignificantly affected by pressure drag forces acting against the upperwheel forward-facing profile surfaces, than for bicycles with thin tiresand rims.

Thus for trucks, deflecting upper wheel headwinds downward onto thelower wheel becomes an important operating function. Since propulsivecounterforces at the axle have a mechanical advantage over lower wheeldrag forces applied to the wheel below the level of the axle, deflectingheadwinds downward onto the lower wheel can reduce overall vehicle dragand improve propulsive efficiency.

In consideration of further embodiments described below, the operatingprinciples described above will generally apply, and may be referredthereto.

Second Embodiment FIGS. 1 and 3

As shown in FIGS. 1 and 3, an embodiment comprises an inclinedaerodynamic deflector panel assembly 15 attached to and mountedunderneath the body of a trailer 16 for a commercial vehicle. Theinclined deflector panel assembly 15 is located forward of the rearwheel assembly 17 and located in front of trailing wheel sets 18 whichwould otherwise be exposed to headwinds when the vehicle is in forwardmotion. The inclined deflector panel assembly 15 is planar in shape,mounted inclined in a forwardly-angled orientation with the upper edgemore forwardly located and the lower surface more rearwardly located onthe vehicle. The inclined deflector panel assembly 15 spans the lateralwidth of the trailer 17, and where aligned directly in front of thewheel sets 18 extends no lower than the level of the axle. The inclineddeflector panel assembly 15 is located proximal to the trailing wheelassembly 18 in order to deflect headwinds onto the exposed lower wheelsurfaces, and to deflect headwinds from directly impinging the centralaxle assembly 19, thereby reducing overall vehicle drag and improvingpropulsive efficiency.

Third Embodiment FIGS. 4 and 5

As shown in FIGS. 4 and 5, an embodiment comprises a channeledaerodynamic wheel deflector panel assembly 25 attached to and mountedunderneath the body of a trailer 16 for a commercial vehicle. Thechanneled wheel deflector panel assembly 25 is located forward of therear wheel assembly 17 and located directly in front of a trailing wheelset 18 which would otherwise be exposed to headwinds when the vehicle isin forward motion. The channeled wheel deflector panel assembly 25includes a deflector plate 22 which is generally planar in shape,mounted inclined in a forwardly-angled orientation with the upper edgemore forwardly-located and the lower surface more rearwardly-located onthe vehicle. The channeled wheel deflector panel assembly 25 includesforwardly-projecting end plates 24 attached to either side edge of thedeflector plate 22, forming a channeled deflector panel assembly 25 tofunnel headwinds directly onto the lower wheel surfaces, minimizing anyoutwardly deflected headwind from otherwise impinging the trailing upperwheel surfaces.

The channeled wheel deflector panel assembly 25 extends no lower thanthe level of the axle 19 and is located proximal to the trailing wheelset 18 in order to deflect and funnel headwinds onto the exposed lowerwheel surfaces, thereby reducing overall vehicle drag and improvingpropulsive efficiency.

Fourth Embodiment FIGS. 4 and 6

As shown in FIGS. 4 and 6, an embodiment comprises a channeledaerodynamic deflector panel assembly 30 attached to and mountedunderneath the body of a trailer 16 for a commercial vehicle. Thechanneled deflector panel assembly 30 is located forward of the rearwheel assembly 17 and located in front of both trailing wheel sets 18which would otherwise be exposed to headwinds when the vehicle is inforward motion. The channeled deflector panel assembly 30 includes adeflector plate 28 which is generally planar in shape, mounted inclinedin a forwardly-angled orientation with the upper edge moreforwardly-located and the lower surface more rearwardly-located on thevehicle. The deflector plate 28 spans the lateral width of the trailer16, and where directly aligned in front of the wheels extends no lowerthan the level of the axle 19. The channeled deflector panel assembly 30includes forwardly-projecting end plates 32 attached to either side edgeof the deflector plate 28, forming a channeled deflector panel assembly30 to funnel headwinds directly onto the lower wheel surfaces andminimize any outwardly deflected headwind from otherwise impinging thetrailing upper wheel surfaces. Although not shown, between the wheelsets 18, the deflector plate 28 may extend further downward to deflectheadwinds well below the central axle assembly 19.

The channeled deflector panel assembly 30 is located proximal to thetrailing wheel set 18 in order to deflect headwinds onto the exposedlower wheel surfaces, and to deflect headwinds from directly impingingthe central axle assembly 19, thereby reducing overall vehicle drag andimproving propulsive efficiency.

Fifth Embodiment FIGS. 7 and 5

As shown in FIG. 7 in side view, and as shown in FIG. 5 when viewed incross-section from the front of the vehicle, an embodiment comprises thechanneled aerodynamic wheel deflector panel assembly 25 identical tothat of the third embodiment above, together with removeable upper wheelskirt panels 38 covering the outside of the trailing wheel sets 18. Theupper wheel skirt panels 38 also extend no lower than the level of theaxle 19.

The upper wheel skirt panels 38 extend from the deflector plate 22rearward to cover adjacent trailing wheel sets 18, thereby shielding thetrailing upper wheels from external headwinds. The channeled wheeldeflector panel assembly 25 used in combination with the upper wheelskirt panels 38 reduces overall vehicle drag and improves propulsiveefficiency.

Sixth Embodiment FIGS. 7 and 6

As shown in FIG. 7 in side view, and as shown in FIG. 6 when viewed incross-section from the front of the vehicle, an embodiment comprises thechanneled aerodynamic deflector panel assembly 30 identical to that ofthe fourth embodiment above, together with removeable upper wheel skirtpanels 38 covering the outside of the trailing wheel sets 18. The upperwheel skirt panels 38 also extend no lower than the level of the axle19.

The upper wheel skirt panels 38 extend from the deflector plate 28rearward to cover adjacent trailing wheel sets 18, thereby shielding thetrailing upper wheels from external headwinds. The channeled deflectorpanel assembly 30 used in combination with the upper wheel skirt panels38 reduces overall vehicle drag and improves propulsive efficiency.

Seventh Embodiment FIGS. 8 and 2

As shown in FIG. 8 in side view, and as shown in FIG. 2 when viewed incross-section from the front of the vehicle, an embodiment comprises anaerodynamic wheel deflector panel 45 is attached to and mountedunderneath the body of a trailer 16 for a commercial vehicle. The wheeldeflector panel 45 is located forward of the rear wheel assembly 17 andlocated in front of a trailing wheel set 18 which would otherwise beexposed to headwinds when the vehicle is in forward motion. The wheeldeflector panel 45 is planar in shape, sufficiently wide to deflectheadwinds from directly impinging the upper wheels of the trailing wheelset, mounted vertically and shown oriented parallel to the axle 19. Thewheel deflector panel 45 extends no lower than the level of the axle 19and is located proximal to the trailing wheel set 18 in order to deflectheadwinds substantially toward either the outside or the inside of thewheel set 18, or onto the lower wheel surfaces, thereby reducing overallvehicle drag and improving propulsive efficiency.

This simple wheel deflector panel configuration is appropriate for usewhen limited clearance space exists in front of the trailing wheel set.

Eighth Embodiment FIGS. 8 and 3

As shown in FIG. 8 in side view, and as shown in FIG. 3 when viewed incross-section from the front of the vehicle, an embodiment comprises anaerodynamic deflector panel 50 is attached to and mounted underneath thebody of a trailer 16 for a commercial vehicle. The deflector panel 50 islocated forward of the rear wheel assembly 17 and located in front of atrailing wheel sets 18 which would otherwise be exposed to headwindswhen the vehicle is in forward motion. The deflector panel 50 is planarin shape, spans the lateral width of the trailer 16, and where aligneddirectly in front of the wheel sets 18 extends no lower than the levelof the axle 19. The deflector panel 50 is mounted vertically andparallel to the axle 19. The deflector panel 50 is located proximal tothe trailing wheel sets 18 in order to deflect headwinds substantiallytoward either the outside of the trailing upper wheels, under thecentral axle assembly, or onto the lower wheel surfaces, therebyreducing overall vehicle drag and improving propulsive efficiency.

This simple deflector panel configuration is appropriate for use whenlimited clearance space exists in front of the trailing wheel assembly.

Ninth Embodiment FIGS. 9 and 2

As shown in FIG. 9 in side view, and similar to as shown in FIG. 2 whenviewed in cross-section from the front of the vehicle, an embodimentcomprises the aerodynamic wheel deflector panel 45 identical to that ofthe seventh embodiment above, together with removeable upper wheel skirtpanels 42 covering the outside of the trailing wheel sets 18. The upperwheel skirt panels 42 also extend no lower than the level of the axle19.

The upper wheel skirt panels 42 extend from the deflector panel 45rearward to cover adjacent trailing wheel sets 18, thereby shielding thetrailing upper wheels from external headwinds. The wheel deflector panel45 used in combination with the upper wheel skirt panels 42 reducesoverall vehicle drag and improves propulsive efficiency.

This simple wheel deflector panel configuration is appropriate for usewhen limited clearance space exists in front of the wheel sets and wherethe use of exterior wheel skirts panels is permitted.

Tenth Embodiment FIGS. 9 and 3

As shown in FIG. 9 in side view, and similar to as shown in FIG. 3 whenviewed in cross-section from the front of the vehicle, an embodimentcomprises the aerodynamic wheel deflector panel 50 identical to that ofthe eight embodiment above, together with removeable upper wheel skirtpanels 42 as used in the ninth embodiment above. The deflector panel 50used in combination with the upper wheel skirt panels 42 reduces overallvehicle drag and improves propulsive efficiency.

This simple wheel deflector panel configuration is appropriate for usewhen limited clearance space exists in front of the wheel sets, wheredeflecting headwinds from directly impinging the central axle assembly19 is needed, and where the use of exterior wheel skirts panels ispermitted.

Eleventh Embodiment FIGS. 10 and 13

As shown in FIGS. 10 and 13, an embodiment comprises an aerodynamicvehicle skirt assembly 60 is attached to and mounted underneath the bodyof a trailer 16 for a commercial vehicle. The vehicle skirt assembly 60is located forward of the rear wheel assembly 17 which would otherwisebe exposed to headwinds when the vehicle is in forward motion. Thevehicle skirt assembly 60 extends down no lower than the level of theaxle 19 of the trailing wheel set 18, leaving lower wheel surfaces ofthe trailing wheel set 18 exposed to headwinds.

The vehicle skirt assembly 60 is shown mounted to the trailer 16 withthe fowardmost end of the vehicle skirt assembly 60 inset toward thecenterline of the trailer 16 to a position in general longitudinalalignment with the inside of—and thereby substantially in front of—theinnermost surface of the trailing wheel set 18. Extending rearward, thevehicle skirt assembly 60 progressively varys in position toward theoutside of the body of the trailer 16, extending more rapidly toward theoutside wheel when nearest the rear end, which is located proximate tothe trailing wheel set 18. The rear end of the vehicle skirt assembly 60is located near the outerside of the wheel set 18, thereby deflectingheadwinds substantially toward the outside of the upper wheel surfacesand below onto the lower wheel surfaces.

The vehicle skirt assembly 60 may be constructed from either a singlepanel or from multiple panels arranged end-to-end. The vehicle skirtassembly 60 may be constructed with resilient materials, especiallyalong the lower edge which may occasionally contact road obstacles. Thevehicle skirt assembly 60 may also be mounted to the trailer 16 bydeflectably resilient means, returning the vehicle skirt assembly 60 tothe proper aerodynamic position after contacting road obstacles.

Twelveth Embodiment FIG. 14

As shown in FIG. 14, an embodiment comprises the aerodynamic vehicleskirt assembly 60 identical to that of the eleventh embodiment above,together with removeable upper wheel skirt panels 42 covering theoutside of the trailing wheel sets 18 as used in the tenth embodimentabove.

The upper wheel skirt panels 42 extend from the aerodynamic vehicleskirt assembly 60 rearward to cover adjacent trailing wheel sets 18,thereby shielding the trailing upper wheels from external headwinds. Theaerodynamic vehicle skirt assembly 60 used in combination with the upperwheel skirt panels 42 reduces overall vehicle drag and improvespropulsive efficiency.

ADVANTAGES

From the description above, a number of advantages of some embodimentsbecome evident:

-   -   (a) An improved aerodynamic wheel set deflector panel located in        front of trailing wheels and extending no lower than the axle to        thereby deflect headwinds onto mechanically disadvantaged lower        wheel surfaces and to shield trailing mechanically-advantaged        upper wheel surfaces from headwinds, thereby reduces overall        vehicle drag improving propulsive efficiency.    -   (b) An improved aerodynamic wheel assembly deflector panel which        may deflect headwinds below the central axle assembly, and where        in front of trailing wheels extending no lower than the axle to        thereby deflect headwinds onto mechanically disadvantaged lower        wheel surfaces and to shield trailing mechanically-advantaged        upper wheel surfaces from headwinds, thereby reduces overall        vehicle drag improving propulsive efficiency.    -   (c) An improved aerodynamic deflector and skirt assembly where        in front of trailing wheels extending no lower than the axle to        thereby deflect headwinds onto mechanically disadvantaged lower        wheel surfaces and to shield trailing mechanically-advantaged        upper wheel surfaces from headwinds, thereby reduces overall        vehicle drag improving propulsive efficiency.    -   (d) An improved aerodynamic vehicle skirt panel assembly        extending no lower than the axle to thereby deflect headwinds        onto mechanically disadvantaged lower wheel surfaces and to        shield trailing mechanically-advantaged upper wheel surfaces        from headwinds, reduces total weight of the skirt assembly,        improves the skirt ground clearance of road obstacles, and        reduces overall vehicle drag improving propulsive efficiency.

CONCLUSIONS, RAMIFICATIONS, AND SCOPE

Exposed wheels can generate considerable drag forces on a movingvehicle. These forces are directed principally near the top of thewheel, rather than being more evenly distributed across the entireprofile of the wheel. Furthermore, these upper-wheel drag forces arelevered against the axle, thereby magnifying the counterforce requiredto propel the vehicle. As a result, a reduction in drag upon the upperwheel generally enhances propulsive efficiency significantly more than acorresponding drag reduction on other parts of the vehicle.

Moreover, since the lower wheel drag forces suffer a mechanicaldisadvantage over propulsive counterforces, using shielding devices todeflect headwinds from impinging lower wheel surfaces can increaseoverall vehicle drag. Given these considerations, it becomes evidentthat drag-reducing vehicle deflectors and skirts should be limited tolengths that inhibit vehicle headwinds from directly impinging only theupper wheel surfaces, leaving the lower wheel surfaces exposed.

While the embodiments shown illustrate application generally to thetrailers of industrial trucks, the embodiments could be similarlyapplied other trucks and vehicle types having wheel assemblies exposedto headwinds. And while the embodiments shown include skirt assembliesformed from relatively inexpensive flat panels, somewhat curved panelscould also be used. Further examples of alternative embodiments includehaving deflector panels mounted at various angles, all limited in heightto extend downward no lower than the level of the axle. Although notshown, in the case where additional space exists in front of the wheelassembly, the wheel deflector panel of the ninth embodiment couldinstead be mounted in nonparallel to the axle in order to deflect windsnot only downward, but also to either side of the trailing wheelassembly.

In addition, the embodiments generally can include various methods ofresilient mounting to the vehicle body permitting the panels to deflectwhen impacted by road obstructions and return undamaged to their normalaerodynamic position.

Accordingly, the embodiments should not be limited to the specificexamples illustrated and described above, but rather to the appendedclaims and their legal equivalents.

1.-20. (canceled)
 21. An apparatus for increasing the propulsiveefficiency of a wheeled vehicle, the vehicle having a vehicle bodysupported thereunder by a rearward wheel assembly wherein when thevehicle is in forward motion under a range of external headwindconditions including null headwind conditions the wheel assembly isotherwise exposed to an oncoming headwind impinging substantiallyunimpeded above the level of an axle directly upon a forward-facingupper circumferential surface of a tire of a wheel of the wheelassembly, comprising: an aerodynamic wind-deflecting deflector panelassembly further comprising one or more panels extending laterallyunderneath the vehicle body and being disposed attachably thereto; thedeflector panel assembly being disposed in part upstream immediately infront of a trailing wheel set comprising one or more said wheels locatedon one of either lateral side of the wheel assembly; the deflector panelassembly further comprising a section of the panels comprising thosesurfaces of said panels which are aligned upstream directly ahead of anyforward-facing upper circumferential tire surface of the trailing wheelset being itself disposed both to extend substantially across thelateral width of the trailing wheel set and to extend not lower than thelevel of the axle; the deflector panel assembly further comprising aplurality of lateral end plates with each said end plate disposedattachably to one of either of the lateral sides of the deflector panelassembly and arranged parallel to the lengthwise sides of the vehiclebody and projecting forwardly to form a channel-shaped deflector panelassembly; the deflector panel assembly being further disposed to exposelower wheel surfaces located below the level of the axle to impingingheadwinds; the deflector panel assembly being further disposed to divertsaid headwind from otherwise impinging directly upon the forward-facingupper circumferential tire surface; and the deflector panel assemblybeing further disposed at a forwardly inclined angle to deflect andchannel said headwind in substantial part both downward below saidaligned upstream section of the panels and rearward onto an exposedforward-facing lower wheel surface of the trailing wheel set, wherebywhen the vehicle is operated nominally under null wind conditions saidaligned upstream section of the panels is both sufficient in totalwind-deflecting extent but limited in total drag-inducing extent toyield sufficiently reduced drag on the primary vehicle-drag-inducingupper wheel surface of the trailing wheel set to increase vehiclepropulsive efficiency more than any increased drag on the slower movingmechanically disadvantaged lower wheel surfaces of the trailing wheelset combined with the drag induced on said aligned upstream section ofthe panels itself decreases vehicle propulsive efficiency and wherebythe vehicle propulsory counterforce needed to countervail an effectivevehicle drag force comprising a mechanically magnified upper wheel dragforce upon the upper wheel surfaces combined with both a non-magnifiedvehicle frame drag force from headwinds impinging on said alignedupstream section of the panels itself attached directly to the vehiclebody and with a mechanically de-magnified lower wheel drag force uponthe lower wheel surfaces is reduced.
 22. The apparatus of claim 21,further comprising the deflector panel assembly further comprising awheel skirt panel assembly located adjacent to outside lateral surfacesof the trailing wheel set and extending downwards from the vehicle bodyto not lower than the level of the axle wherein substantial uppermostsurfaces on the outer lateral sides of the adjacent trailing wheel setare largely shielded from oncoming headwinds otherwise impingingthereon.
 23. The apparatus of claim 21, further comprising the deflectorpanel assembly wherein said aligned upstream section of the panels beingdisposed to extend not lower than a level in elevation equal to sixtypercent of the outer diameter of the trailing wheel set.
 24. Theapparatus of claim 21, further comprising the deflector panel assemblyfurther comprising a wheel skirt panel assembly located adjacent tooutside lateral surfaces of the trailing wheel set and extendingdownwards from the vehicle body to not lower than a level in elevationequal to sixty percent of the outer diameter of the wheel set whereinsubstantial uppermost surfaces on the outer lateral sides of theadjacent trailing wheel set are largely shielded from oncoming headwindsotherwise impinging thereon.
 25. An apparatus for increasing thepropulsive efficiency of a wheeled vehicle, the vehicle having a vehiclebody supported thereunder by a rearward wheel assembly wherein when thevehicle is in forward motion under a range of external headwindconditions including null headwind conditions the wheel assembly isotherwise exposed to an oncoming headwind impinging substantiallyunimpeded above the level of an axle directly upon a forward-facingupper circumferential surface of a tire of a wheel of the wheelassembly, comprising: an aerodynamic wind-deflecting deflector panelassembly further comprising one or more panels extending laterallyunderneath the vehicle body and being disposed attachably thereto; thedeflector panel assembly being disposed in part upstream immediately infront of a trailing wheel set comprising one or more said wheels locatedon one of either lateral side of the wheel assembly; the deflector panelassembly further comprising a section of the panels comprising thosesurfaces of said panels which are aligned upstream directly ahead of anyforward-facing upper circumferential tire surface of the trailing wheelset being itself disposed both to extend substantially across thelateral width of the trailing wheel set and to extend not lower than thelevel of the axle; the deflector panel assembly being further disposedto expose lower wheel surfaces located below the level of the axle toimpinging headwinds; the deflector panel assembly being further disposedto divert said headwind from otherwise impinging directly upon theforward-facing upper circumferential tire surface; the deflector panelassembly being further disposed to deflect said headwind in substantialpart downward below said aligned upstream section of the panels wherethe downwardly deflected headwind impinges upon an exposedforward-facing lower wheel surface of the trailing wheel set; andwherein when the vehicle is operated nominally under null windconditions said aligned upstream section of the panels is bothsufficient in total wind-deflecting extent but limited in totaldrag-inducing extent to yield sufficiently reduced drag on the primaryvehicle-drag-inducing upper wheel surface of the trailing wheel set toincrease vehicle propulsive efficiency more than any increased drag onthe slower moving mechanically disadvantaged lower wheel surfaces of thetrailing wheel set combined with the drag induced on said alignedupstream section of the panels itself decreases vehicle propulsiveefficiency whereby the vehicle propulsory counterforce needed tocountervail an effective vehicle drag force comprising a mechanicallymagnified upper wheel drag force upon the upper wheel surfaces combinedwith both a non-magnified vehicle frame drag force from headwindsimpinging on said aligned upstream section of the panels itself attacheddirectly to the vehicle body and with a mechanically de-magnified lowerwheel drag force upon the lower wheel surfaces is reduced.
 26. Theapparatus of claim 25, further comprising the deflector panel assemblydisposed at a forwardly inclined angle to deflect oncoming headwindsotherwise impinging on the forward-facing upper circumferential tiresurface both downward and rearward onto the exposed forward-facing lowerwheel surface.
 27. The apparatus of claim 25, further comprising: thedeflector panel assembly further comprising a plurality of lateral endplates with each said end plate disposed attachably to one of either ofthe lateral sides of the deflector panel assembly and arranged parallelto the lengthwise sides of the vehicle body and projecting forwardly toform a channel-shaped deflector panel assembly; and the deflector panelassembly disposed at a forwardly inclined angle to deflect and channeloncoming headwinds otherwise impinging on the forward-facing uppercircumferential tire surface both downward and rearward onto the exposedforward-facing lower wheel surface.
 28. The apparatus of claim 25,further comprising: the deflector panel assembly further comprising aplurality of lateral end plates with each said end plate disposedattachably to one of either of the lateral sides of the deflector panelassembly and arranged parallel to the lengthwise sides of the vehiclebody and projecting forwardly to form a channel-shaped deflector panelassembly; the deflector panel assembly disposed at a forwardly inclinedangle to deflect and channel oncoming headwinds otherwise impinging onthe forward-facing upper circumferential tire surface both downward andrearward onto the exposed forward-facing lower wheel surface; and thedeflector panel assembly further comprising a wheel skirt panel assemblylocated adjacent to outside lateral surfaces of the trailing wheel setand extending downwards from the vehicle body to not lower than thelevel of the axle wherein substantial uppermost surfaces on the outerlateral sides of the adjacent trailing wheel set are largely shieldedfrom oncoming headwinds otherwise impinging thereon.
 29. The apparatusof claim 25, further comprising the deflector panel assembly wherein thedeflector panel assembly is suspended in a substantially verticalorientation.
 30. The apparatus of claim 25, further comprising: thedeflector panel assembly wherein the deflector panel assembly issuspended in a substantially vertical orientation; and the deflectorpanel assembly further comprising a wheel skirt panel assembly locatedadjacent to outside lateral surfaces of the trailing wheel set andextending downwards from the vehicle body to not lower than the level ofthe axle wherein substantial uppermost surfaces on the outer lateralsides of the adjacent trailing wheel set are largely shielded fromoncoming headwinds otherwise impinging thereon.
 31. The apparatus ofclaim 25, further comprising: the deflector panel assembly disposed at aforwardly inclined angle to deflect oncoming headwinds otherwiseimpinging on the forward-facing upper circumferential tire surface bothdownward and rearward onto the exposed forward-facing lower wheelsurface; and the deflector panel assembly further comprising a wheelskirt panel assembly located adjacent to outside lateral surfaces of thetrailing wheel set and extending downwards from the vehicle body to notlower than the level of the axle wherein substantial uppermost surfaceson the outer lateral sides of the adjacent trailing wheel set arelargely shielded from oncoming headwinds otherwise impinging thereon.32. The apparatus of claim 25, further comprising: the deflector panelassembly disposed at a forwardly inclined angle to deflect oncomingheadwinds otherwise impinging on the forward-facing uppercircumferential tire surface both downward and rearward onto the exposedforward-facing lower wheel surface; and the deflector panel assemblyfurther comprising a wheel skirt panel assembly located adjacent tooutside lateral surfaces of the trailing wheel set and extendingdownwards from the vehicle body to not lower than a level in elevationequal to sixty percent of the outer diameter of the trailing wheel setwherein substantial uppermost surfaces on the outer lateral sides of theadjacent trailing wheel set are largely shielded from oncoming headwindsotherwise impinging thereon.
 33. The apparatus of claim 25, furthercomprising the deflector panel assembly further comprising a wheel skirtpanel assembly located adjacent to outside lateral surfaces of thetrailing wheel set and extending downwards from the vehicle body to notlower than a level in elevation equal to sixty percent of the outerdiameter of the trailing wheel set wherein substantial uppermostsurfaces on the outer lateral sides of the adjacent trailing wheel setare largely shielded from oncoming headwinds otherwise impingingthereon.
 34. An apparatus for increasing the propulsive efficiency of awheeled vehicle, the vehicle having a vehicle body supported thereunderby a rearward wheel assembly wherein when the vehicle is in forwardmotion under a range of external headwind conditions including nullheadwind conditions the wheel assembly is otherwise exposed to anoncoming headwind impinging substantially unimpeded above the level ofan axle directly upon a forward-facing upper circumferential surface ofa tire of a wheel of the wheel assembly, comprising: an aerodynamicwind-deflecting deflector panel assembly further comprising one or morepanels extending in part laterally underneath the vehicle body and beingdisposed attachably thereto; the deflector panel assembly being disposedin part upstream immediately in front of a trailing wheel set comprisingone or more said wheels located on one of either lateral side of thewheel assembly; the deflector panel assembly further comprising asection of the panels comprising those surfaces of said panels which arealigned upstream directly ahead of any forward-facing uppercircumferential tire surface of the trailing wheel set being itselfdisposed both to extend substantially across the lateral width of thetrailing wheel set and to extend not lower than a level in elevationequal to sixty percent of the outer diameter of the trailing wheel set;the deflector panel assembly being further disposed to expose lowerwheel surfaces located below the level of the axle to impingingheadwinds; the deflector panel assembly being further disposed to divertsaid headwind from otherwise impinging directly upon the forward-facingupper circumferential tire surface; the deflector panel assembly beingfurther disposed to deflect said headwind in substantial part downwardbelow said aligned upstream section of the panels where the downwardlydeflected headwind impinges upon an exposed forward-facing lower wheelsurface of the trailing wheel set; and wherein when the vehicle isoperated nominally under null wind conditions said aligned upstreamsection of the panels is both sufficient in total wind-deflecting extentbut limited in total drag-inducing extent to yield sufficiently reduceddrag on the primary vehicle-drag-inducing upper wheel surface of thetrailing wheel set to increase vehicle propulsive efficiency more thanany increased drag on the slower moving mechanically disadvantaged lowerwheel surfaces of the trailing wheel set combined with the drag inducedon said aligned upstream section of the panels itself decreases vehiclepropulsive efficiency whereby the vehicle propulsory counterforce neededto countervail an effective vehicle drag force comprising a mechanicallymagnified upper wheel drag force upon the upper wheel surfaces combinedwith both a non-magnified vehicle frame drag force from headwindsimpinging on said aligned upstream section of the panels itself attacheddirectly to the vehicle body and with a mechanically de-magnified lowerwheel drag force upon the lower wheel surfaces is reduced.
 35. Theapparatus of claim 34, further comprising: the deflector panel assemblyextending laterally underneath the vehicle body; and the deflector panelassembly disposed at a forwardly inclined angle to deflect oncomingheadwinds otherwise impinging on the forward-facing uppercircumferential tire surface both downward and rearward onto the exposedforward-facing lower wheel surface.
 36. The apparatus of claim 34,further comprising: the deflector panel assembly extending laterallyunderneath the vehicle body; the deflector panel assembly furthercomprising a plurality of lateral end plates with each said end platedisposed attachably to one of either of the lateral sides of thedeflector panel assembly and arranged parallel to the lengthwise sidesof the vehicle body and projecting forwardly to form a channel-shapeddeflector panel assembly; and the deflector panel assembly disposed at aforwardly inclined angle to deflect and channel oncoming headwindsotherwise impinging on the forward-facing upper circumferential tiresurface both downward and rearward onto the exposed forward-facing lowerwheel surface.
 37. The apparatus of claim 34, further comprising: thedeflector panel assembly extending laterally underneath the vehiclebody; the deflector panel assembly further comprising a plurality oflateral end plates with each said end plate disposed attachably to oneof either of the lateral sides of the deflector panel assembly andarranged parallel to the lengthwise sides of the vehicle body andprojecting forwardly to form a channel-shaped deflector panel assembly;the deflector panel assembly disposed at a forwardly inclined angle todeflect and channel oncoming headwinds otherwise impinging on theforward-facing upper circumferential tire surface both downward andrearward onto the exposed forward-facing lower wheel surface; and thedeflector panel assembly further comprising a wheel skirt panel assemblylocated adjacent to outside lateral surfaces of the trailing wheel setand extending downwards from the vehicle body to not lower than thelevel of the axle wherein substantial uppermost surfaces on the outerlateral sides of the adjacent trailing wheel set are largely shieldedfrom oncoming headwinds otherwise impinging thereon.
 38. The apparatusof claim 34, further comprising the deflector panel assembly extendinglaterally underneath the vehicle body wherein the deflector panelassembly is suspended in a substantially vertical orientation.
 39. Theapparatus of claim 34, further comprising: the deflector panel assemblyextending laterally underneath the vehicle body wherein the deflectorpanel assembly is suspended in a substantially vertical orientation; andthe deflector panel assembly further comprising a wheel skirt panelassembly located adjacent to outside lateral surfaces of the trailingwheel set and extending downwards from the vehicle body to not lowerthan the level of the axle wherein substantial uppermost surfaces on theouter lateral sides of the adjacent trailing wheel set are largelyshielded from oncoming headwinds otherwise impinging thereon.
 40. Theapparatus of claim 34, further comprising the deflector panel assemblydisposed with a leading end thereof located forward and inboard towardthe centerline of the vehicle body and with a trailing end thereoflocated outboard proximate to the outside lateral surface of theoutermost wheel of the wheel set wherein the deflector panel assemblycomprises a vehicle skirt assembly located largely lengthwise along alongitudinal side of the vehicle.
 41. The apparatus of claim 34, furthercomprising the deflector panel assembly disposed with a leading endthereof located forward and inboard toward the centerline of the vehiclebody and with a trailing end thereof located outboard proximate to theoutside lateral surface of the outermost wheel of the wheel set and witha intermediate portion thereof located substantially rearward near toand longitudinally aligned in front of the inward lateral surface of theinnermost wheel of the wheel set wherein the deflector panel assemblycomprises a vehicle skirt assembly located largely lengthwise along alongitudinal side of the vehicle.
 42. The apparatus of claim 34, furthercomprising: the deflector panel assembly extending laterally underneaththe vehicle body; the deflector panel assembly disposed at a forwardlyinclined angle to deflect oncoming headwinds otherwise impinging on theforward-facing upper circumferential tire surface both downward andrearward onto the exposed forward-facing lower wheel surface; and thedeflector panel assembly further comprising a wheel skirt panel assemblylocated adjacent to outside lateral surfaces of the trailing wheel setand extending downwards from the vehicle body to not lower than thelevel of the axle wherein substantial uppermost surfaces on the outerlateral sides of the adjacent trailing wheel set are largely shieldedfrom oncoming headwinds otherwise impinging thereon.
 43. The apparatusof claim 34, further comprising: the deflector panel assembly extendinglaterally underneath the vehicle body; the deflector panel assemblydisposed at a forwardly inclined angle to deflect oncoming headwindsotherwise impinging on the forward-facing upper circumferential tiresurface both downward and rearward onto the exposed forward-facing lowerwheel surface; and the deflector panel assembly further comprising awheel skirt panel assembly located adjacent to outside lateral surfacesof the trailing wheel set and extending downwards from the vehicle bodyto not lower than a level in elevation equal to sixty percent of theouter diameter of the trailing wheel set wherein substantial uppermostsurfaces on the outer lateral sides of the adjacent trailing wheel setare largely shielded from oncoming headwinds otherwise impingingthereon.
 44. The apparatus of claim 34, further comprising: thedeflector panel assembly extending laterally underneath the vehiclebody; and the deflector panel assembly further comprising a wheel skirtpanel assembly located adjacent to outside lateral surfaces of thetrailing wheel set and extending downwards from the vehicle body to notlower than a level in elevation equal to sixty percent of the outerdiameter of the trailing wheel set wherein substantial uppermostsurfaces on the outer lateral sides of the adjacent trailing wheel setare largely shielded from oncoming headwinds otherwise impingingthereon.
 45. A method for increasing the propulsive efficiency of awheeled vehicle, the vehicle having a vehicle body supported thereunderby a rearward wheel assembly wherein when the vehicle is in forwardmotion under a range of external headwind conditions including nullheadwind conditions the wheel assembly is otherwise exposed to anoncoming headwind impinging substantially unimpeded above the level ofan axle directly upon a forward-facing upper circumferential surface ofa tire of a wheel of said wheel assembly, comprising: first, forming anaerodynamic wind-deflecting deflector panel assembly; next, attaching anupperward portion of the deflector panel assembly to a lower surface ofthe vehicle body wherein the deflector panel assembly is largelysuspended from the vehicle body and disposed attachably thereto whilealso being disposed in part upstream immediately in front of a trailingwheel set comprising one or more said wheels located on one of eitherlateral side of the wheel assembly and wherein a wind-deflecting sectionof the deflector panel assembly which comprises those surfaces of saidpanels which are aligned upstream directly ahead of any forward-facingupper circumferential tire surface of the trailing wheel set extendssubstantially across the lateral width of the trailing wheel set and isdisposed to extend not lower than the level of the axle; then, arrangingthe deflector panel assembly wherein said aligned upstreamwind-deflecting section being itself substantially limited in totalwind-deflecting extent; and furthermore arranging said aligned upstreamwind-deflecting section to be both disposed in sufficient proximity tothe trailing wheel set and arranged wherein a headwind otherwiseimpinging on a primary vehicle-drag-inducing upper wheel surface of afrontal upper half-section of a wheel of the trailing wheel set isdeflected in substantial part downward below the deflector panelassembly onto an exposed forward-facing lower wheel surface of thetrailing wheel set and wherein when the vehicle is operated nominallyunder null wind conditions said aligned upstream wind-deflecting sectionis both sufficient in total wind-deflecting extent but limited in totaldrag-inducing extent to yield sufficiently reduced drag on the primaryvehicle-drag-inducing upper wheel surface of the trailing wheel set toincrease vehicle propulsive efficiency more than any increased drag onthe slower moving mechanically disadvantaged lower wheel surfacescombined with the drag induced on said aligned upstream wind-deflectingsection itself decreases vehicle propulsive efficiency whereby thevehicle propulsory counterforce needed to countervail an effectivevehicle drag force comprising a mechanically magnified upper wheel dragforce upon the upper wheel surfaces combined with both a non-magnifiedvehicle frame drag force from headwinds impinging on said alignedupstream wind-deflecting section itself attached directly to the vehiclebody and with a mechanically de-magnified lower wheel drag force uponthe lower wheel surfaces is reduced.
 46. In combination, a vehiclehaving a vehicle body supported thereunder by a rearward wheel assemblyotherwise exposed to headwinds impinging substantially unimpeded abovethe level of an axle directly upon a forward-facing uppercircumferential surface of a tire of a wheel of a wheel set located onone of either lateral side of said wheel assembly when the vehicle is inforward motion under a range of external headwind conditions includingnull headwind conditions and a wind diverting means for increasing thepropulsive efficiency of the vehicle wherein said wind diverting meansis largely suspended from underneath the vehicle body attachablythereto, and wherein said wind diverting means is disposed wholly abovethe level of the axle, and wherein said wind diverting means is disposedin part upstream immediately in front of the forward-facing uppercircumferential tire surface of the trailing wheel set, and wherein saidwind diverting means is disposed in part upstream immediately in frontof a major proportion of the primary vehicle-drag-inducing upper wheelsurfaces of the forward-facing upper circumferential tire surfaces ofthe trailing wheel set located above a level in elevation equal to sixtypercent of the outer diameter of the trailing wheel set, and whereinsaid wind diverting means is disposed to divert headwinds from otherwiseimpinging directly on said major proportion of the primaryvehicle-drag-inducing upper wheel surfaces by diverting a substantialpart of oncoming headwinds otherwise impinging thereon downwardly ontoslower moving mechanically disadvantaged lower wheel surfaces, andwherein when the vehicle is operated nominally under null windconditions said wind diverting means diverts sufficient said substantialpart of oncoming headwinds from otherwise impinging directly upon saidmajor proportion of the primary vehicle-drag-inducing upper wheelsurfaces without inducing too much additional drag on said winddiverting means itself to yield sufficiently reduced drag on the primaryvehicle-drag-inducing upper wheel surfaces of the trailing wheel set toproduce an increase in vehicle propulsive efficiency exceeding anydecrease in vehicle propulsive efficiency caused by any increased dragon the lower wheel surfaces combined with any drag induced directly onthe vehicle from said substantial part of oncoming headwinds beingdiverted by said wind diverting means itself whereby the vehiclepropulsory counterforce needed to countervail an effective vehicle dragforce comprising a mechanically magnified upper wheel drag force uponthe upper wheel surfaces combined with both a non-magnified vehicleframe drag force from said substantial part of oncoming headwinds beingdiverted by said wind diverting means itself attached directly to thevehicle body and with a mechanically de-magnified lower wheel drag forceupon the lower wheel surfaces is reduced.
 47. The wind diverting meansof claim 46, further comprising said wind diverting means disposed toextend laterally underneath the vehicle body while being arranged todivert said substantial part of oncoming headwinds both downward andrearward.
 48. The wind diverting means of claim 46, further comprisingsaid wind diverting means disposed to extend laterally underneath thevehicle body to divert the headwinds both downward and rearward whereinsaid substantial part of oncoming headwinds are substantially channeledwithin a largely non-dispersive flow stream located proximally adjacentto said wind diverting means.
 49. The wind diverting means of claim 46,further comprising: said wind diverting means disposed in part to extendlaterally underneath the vehicle body while being arranged to divertsaid substantial part of oncoming headwinds both downward and rearwardwherein said substantial part of oncoming headwinds are substantiallychanneled within a largely non-dispersive flow stream located proximallyadjacent to said wind diverting means; and said wind diverting meansdisposed in part downwardly from the vehicle body and proximallyadjacent to outside lateral surfaces of the trailing wheel set to notlower than the level of the axle wherein oncoming headwinds otherwiseimpinging on substantial uppermost surfaces on the outer lateral sidesof the adjacent trailing wheel set are largely diverted from impingingthereon by said wind diverting means positioned intermediatelythere-between.
 50. The wind diverting means of claim 46, furthercomprising said wind diverting means disposed to extend laterallyunderneath the vehicle body in a substantially vertical orientation. 51.The wind diverting means of claim 46, further comprising: said winddiverting means disposed in part to extend laterally underneath thevehicle body in a substantially vertical orientation; and said winddiverting means disposed in part downwardly from the vehicle body andproximally adjacent to outside lateral surfaces of the trailing wheelset to not lower than the level of the axle wherein oncoming headwindsotherwise impinging on substantial uppermost surfaces on the outerlateral sides of the adjacent trailing wheel set are largely divertedfrom impinging thereon by said wind diverting means positionedintermediately there-between.
 52. The wind diverting means of claim 46,further comprising: said wind diverting means disposed to extendlaterally underneath the vehicle body; said wind diverting meansdisposed wholly upstream and aligned solely directly ahead of thetrailing wheel set; and the portion of said wind diverting meansdiverting downwardly said substantial part of oncoming headwinds beingitself disposed wholly above a level in elevation equal to sixty percentof the outer diameter of the trailing wheel set.